American citizens escaping Yemen, including small children and some frail elderly, are arriving exhausted in Djibouti after harrowing journeys from the besieged country, where a U.S.-supported Saudi Arabian bombing campaign is entering its fourth week, the U.S. ambassador to the small Horn of Africa country told McClatchy on Thursday.

Calling the flight from Yemen “a tough experience” for many of the evacuees, the U.S. envoy, Tom Kelly, said hundreds of Americans have arrived in Djibouti in recent days aboard foreign ships and aircraft after journeys that for some included hundreds of miles of dangerous land travel from Yemen’s capital, Sanaa, to the ports of Hodeidah and Aden.

In one case, Kelly said, some would-be evacuees were left behind at the port of Aden because they had been unable to climb up rope ladders to board an Indian navy frigate from smaller boats that had ferried them to the larger ship, which had been unable to dock because of fighting in the city.

“Not all were able to get on board,” he said. The 500 or so who did included dozens of Americans, who were brought aboard the frigate, the Tarkesh, to Djibouti on April 11, he said.

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The arrival of American evacuees from Yemen has overwhelmed the diplomatic mission in Djibouti, a former French colony across the Red Sea from Yemen that has just 800,000 residents.

“We don’t have a large embassy, but we’re working around the clock to make sure we can provide care and shelter to everyone coming from Yemen,” he said. Kelly said the U.S. State Department is dispatching more consular affairs officers to Djibouti to help with the expected crush.

How many Americans ultimately will make it to Djibouti is unknown, but Kelly said he is preparing to receive “a large number,” though he cautioned that many who want to leave Yemen may not be able to.

“The situation in Yemen is tough, and it’s hard for people to get out,” he said in a telephone interview.

On Thursday, 59 American citizens, and 40 relatives, were among 400 passengers evacuated from the Red Sea port of Hodeidah by the Indian navy ship the Sumitra, Kelly said.

The Obama administration so far has declined to organize a rescue mission for the estimated 3,000 to 4,000 U.S. citizens in Yemen. U.S. officials have said they believe it is too dangerous for U.S. military assets to enter Yemeni waters and air space. They’ve also suggested that organizing Americans to meet at a single departure point would put them at risk of attack from al Qaida in the Arabian Peninsula or other terrorist groups seeking American hostages.

That, however, has left Americans largely on their own to find a way out of the country. The U.S. Embassy in Sanaa has been closed for months, and the last American troops in the country were evacuated last month, a few days before the Saudi bombing campaign began.

In a message posted on its website, the U.S. Embassy in Sanaa advises that an Indian naval vessel will be leaving Hodeidah for Djibouti and that it had been informed that Americans would be welcomed. But the embassy also noted that “unfortunately, we don’t have information on who to contact to board this ship.”

A few dozen Americans have made it aboard U.N.-organized evacuation flights from Sanaa to Khartoum, Sudan, and others have made it out aboard Russian ships, according to news accounts.

But the largest number seem bound for Djibouti, where Kelly said he travels to the port daily to greet the new arrivals. To date, he said, “I have not seen any people injured,” but he added that many have required medicine or other kind of assistance.

“We have a great team in place and we’re working hard and pulling together to take care of Americans” and non-American family members, he said.

Kelly, a Stanford and Georgetown University-educated veteran diplomat, also praised the efforts of the host country.

“Djibouti is doing a heroic job” in dealing with the influx of refugees and foreign nationals fleeing Yemen, he said. He emphasized that the poor African country will need extra resources.

“Djibouti has a limited capacity to deal with a surge in refugees and will need help,” he said.

Kelly said the U.S. is going to donate 18 metric tons of food to Djibouti, which is looking after Yemeni refugees at a camp outside the city of Obock

“There is a need for food there” he said.

The influx of refugees is likely only to grow. In a report Wednesday, the International Federation of Red Cross and Red Crescent Societies predicted that as many a million people now in Yemen could be expected to flee and that their most likely path out is by sea to Djibouti or nearby Somalia in Africa. The U.N. refugee agency said this week it was making contingency plans to support 30,000 Yemeni refugees in Djibouti and 100,000 in Somalia.

Meanwhile, the office of the U.N. High Commissioner for Human Rights said Thursday that as of Wednesday the civilian death toll had reached 405, including 26 women and 86 children. Senior officials rejected comments by the Saudi ambassador to the United States in Washington suggesting such accounts should be take with a grain of salt.